Electromechanical recording mechanism



Aug. 13, 1929- E. B. STEPHENSON ELECTROMECHANI CAL RECORDING MECHANISM Filed Feb. 13, 1924 ZIIJQZ W Patented Au 13, 1929.

UNIET STTES EDWARD B. STEPHENSON,

F SCHENEGTADY, nnw YORK.

ELECTROMECHANIGAL RECORDING MECHANISM.

Application filed February 13, 1924. Serial no; 692,575.

(GRANTED UNDER THE PROVISIONS OF THE ACT OF MARCH 3, 1883, 22 STAT. L, 625.)

The invention described herein may be used by the Government, or any of its olficers or employees in prosecution of work for the Government, or by any other person in the United States, without payment to me of any royalty thereon.

This invention from' a generic aspect re lates to mechanism for recording time intervals, more especially'it is directed to an 0 el'ectro-mechanical recording apparatus particularly applicable to a subaqueous system of artillery fire adjustment, utilizing water as a transmitting medium, the impact of the projectile striking the water as a source of L5 the pressure .wave and hydrophones as detectors..

In pending application Serial No. 435,510, filed January .6, 1921, there is shown and described a subaqueous system of artillery fire adjustment based on the theory that- (1) a projectile striking the water produces a pressure pulse or wave having a circular wavefront, (2) there is a time intervalbetween the arrival of the pressure wave at two or more stations located at definitely known and equally "distant points, (3) the differences in the time. of arrival at the different stations, taken in connection with the constant known rate of propagation of the pressure wave-in water, will enable determination of the source of the disturbance,

(4:) the sources of the pressure wave likewise'the position of the target being known the correct artillery adjustment can readily be ascertained. 1

In the practical application of this invention, the record o the time interval between the arrival of the pressure pulse or wave at two-or more detector stations was produced either mechanically .by means of a stylus operating on a smoke surface moving at a uniform rate of speed, or photographically through the instrumentality of a spot of light focused on a sensitized paper also travelling at uniform speed.

As time is an ,important factor in the problem of accurately ranging artillery fire, it is obviously imperative that the final result of the fire vbe obtained as quickly as 50 ossible and therefore the several steps coniiibutory to this result must be made'with the least possibly dela For this reason neither the mechanica nor photogra hic recording devices heretofore employed ave been entirely satisfactory.

When the mechanical recorder was utilized, owing to the impossibility'of impressing timing lines transversely across the whole record, measurement of the time interv'al was extremely difiicult, while with the use of the photographic recording mechanism', there was an objectionable time loss due'to the necessity of developing the film before the record could be read.

Moreover, with both of these recording devices it was necessary to algebraically subtract each reading from the preceding" f; one and this involvedan additional loss of time and likewise introduced a further objectionable feature arising from the possibility of personal errors.

It is thereforethe aim and purpose of this ihvention to overcome the defects mentionedand provide an electro-mecha'nical recording mechanism capable oFautomatically functioning to afford a direct reading of the time interval between the arrival of the pressure wave or pulse at two or more suitably spaced detector stations.

With the above and other objects in view this inventipn consists in certain novel details of construction, combination and arrangement of partsto be more specifically hereinafter set forth and claimed.

Briefly stated, this invention embodies a recorder circuit, air of'contact switches included in the circuit, one being normally ;open, the other closed, a pair of detector stations submerged-off shore and arranged in suitably spaced relation, means to effect actuation of the normally open contact switch and completion of the recorder circuit, when a pressure pulse or wave, produced by a projectile striking the water, encounters one of the detector stations, additional means to open the remaining contact switch and disrupt the recorder circuit when the pressure pulse or wave contacts with the companion detector station, and recording means in the recorder circuit adapted to indicate the energized period. of the circuit and consequently the time inter- Fig. 1 is a diagrammatic view illustrating the detector stations, central station, reversing switch, relays, electrb-magnets 'controlling the electro-mechanical recording apparatus, and the operating circuits for these components. I

Fig. 2 is a diagrammatic view'illustrating the listening stations, the direction finders, i and the microphone circuits controlled thereby and disclosing the disposition of'the direction finders with respect to the detector stations, the circuits of which are partially shown.

' Fig. 3 is a front elevation of the electromechanical recording apparatus, and

Fig. 4 is a side elevation thereof.

In order to facilitate discussion of this invention it will be further considered under the following headings:'Detector installation, Central station, Direction finders, Operation and conclusion.

Detector .z'nsttrllation.

To obtain the initial indication of the pressure Wave resulting from a projectile striking the water, a series of hydrophone detector stat-ions, three in number and indicated D D and D, are submerged in equispaced relation and at a sufficient distance off shore to avoid water noises on shore and afford an uninterrupted water path between the stations and the source of the pressure wave or pulse.

As it is essential to the successful opera tion of this invention that the hydrophone detector stations respond only to a characterlstic pressure pulse or wave, a specially designed hydrophone is employed consisting of a rigid shell (1) within which is diametrically positioned a strip of thin spring steel (2) adjustably tensioned for tuning. Affixed to the central portion of the strip (2) is an inertia element in the nature of an iron disc, constituting a movable contact (8). A stationary contact (41-) relatively adjustable with respect to the movable contact (3) is suitably mounted within the shell as shown 1 in Figure 1 of the drawings.

The dimensions of the hydrophone shell, the length, width, thickness, tension of the steel strip, weight of the iron disc or inertia element and relative position of the movable and stationary contacts, are so adjusted and proportioned as to give maximum sensitivity to the characteristic pulse or pressure wave produced by the projectile striking the water, as will be apparent without further discussion.

As the preceding structure forms no part of the present invention, it is referred to merely. for descriptive purposes, therefore shown, more or less diagrammatically in the drawings.

Central station.

The several detectors 1),, D and D are electrically connected with a central station wherein is located an electro-mechanical recording apparatus, functioning to indicate the differences in time of arrival of the pressure wave orpulse at two or more of the detector stations.

This recording apparatus in its present embodiment consists of a suitable frame comprising base (4), parallel uprights (5) and a cross-head (6), suitably braced and connected at its inner end to the uprights The forward edge of the cross-head (6) is provided with a brakeshoe for a pur- 1 pose hereinafter to be described.

Rotatably mounted on the base (4) below the brake-shoe (7) is a large heavy drum (8) driven by a direct current motor (9) through reduction gears (L0). To enable r0- tation of the drum (9) at a constant peripheral speed of 20 cm. per second a governor (11) of conventional type is operatively connected with the motor shaft as clearly shown in Figure 3 of the drawing.

The size of the drum (8) and rotation thereof at constant speed is highly important to the accuracy. of this apparatus and must be such as to prevent change in speed of the drum when the time indicating discs,

hereinafter mentioned, are brought into contact therewith. As the load is constant and the rate of rotation low, no di-iiculty is experienced in governing the driven motor either mechanically or electrically to .05 per- ,cent, which is the required degree of speed control.

Interposed between drum (8) and brakeshoe surface (7) are two light weight discs (12) and (12) each of which is rotatably journall'ed in the forward extremity of an arm (13), the opposite end of which is pivotally mounted on rocker shaft (14). A spring (15) positioned between each of the arms and cross-head (6) normally maintain the discs (12) and (12') in engagement with brake-shoe (7).

The rotary movement of the drum. likewise the relative dimensions of discs and drum are such that the discs (12) and (113) will make one revolution in exactly two seconds. These discs are graduated around their periphery so that two min. equals .01 seconds. In this connection it would be practical to estimate to a tenth of a division thus affording readings to the thousandths of a second.

Assuming a base line of thirty-six yards or less and a pressure pulse velocity of six cm. radius or approximately five and a quarter inches in diameter.

As the discs (12) and (12) are started by contact with drum (8) and stopped by engaging brake-shoe (7), it is evident, a very slight time loss occurs, which, however, may be minimized to a large extent by constructing the brake-shoe (7) of the same material and with the same curvature as the drum (8) so that the starting and stopping processes will be almost identical. Moreover,

this slight time interval, may readily be com-' Y pensated for by shifting the zero point as the error is constant within the required limits of accuracy.

Mounted immediately below and intermediate the extremities of arms (13) are electro-magnets (15') and (16) respectively, positioned to cooperate with the armature surfaces (17) carried by the arms, so that the electro-magnets when energized, will draw. the arms downwardly and place the discs (12) and (12') in contact with themtating drum'(8), for a purpose to hereinafter appear.

To energize the electro-magnet (15) and (16) they are included in circuits 1 and 2, respectively. Circuit 1 comprises battery (18) or other suitable source of electrical energy, conductor (20), electro-magnet (15), conductor (21), contact (22), armature switch (23), conductors (24) and (25), armature switch (27), contact (28 and conductor (29).

Circuit 2, comprises battery (30), conductor (31), electro-magnet (16), conductor (32), contact (33), conductors (35), (25) and (24) armature sw7ich (23), contact (36) and conductor (3 To retam the armature switches (27),

(23) and (34) in a normal position with respect to circuits 1 and 2 each is provided with a retract-ile spring (38)! After actuation of the switches to circuit closing or disrupting positions, they are automatically locked therein by spring latches (39), whic may be manually or electrically released depending on the exigencies of the situation.

The armature switches in conjunction with their respective solenoids constitute relays R R and R which are included in three relay circuits each including a hydrophone detector station D D or D,, reversing switch 'S and one of the relays R R or R The relay circuit including relay R comprises ground connection (40), movable and stationary contacts (3) and (4) of the hy drophone detector station D conductor (41), blade (42) of reversing switch "S, contact- (43), conductor (44), relay R conarmature switch (34),

ductors (45) and (46), battery or other suitable source of electrical energy (47) and ground connection (48).

The relay circuit of detector station D. comprises ground connection (49), movable and stationary contacts (3) and (4) of hydrophone detector station D conductor (50), blade (51) of reversing switch S, contact (52), conductor (53), relay R con ductors (45) and (46), battery (47) and ground connection (48).

The reLay circuit for the conductor station D embodies ground connection (54), movable and stationary contacts (3) and (4) of hydrophone detector station D conductor (54), switch blade (55) of reversing switch S, contact (56), conductor (57), relay 11,, conductors (45) and (46), battery (47) and ground connection (48).

As the relays R R and R are arranged to function in the order mentioned, while the pressure pulse or wave may approach the detector stations D D and D from the right or left, it is necessary to provide for a reversal of the order in which the detector stations effect energization of the relays and foizthispurpose the switch S is formed with reversing contacts (58), (59), and (60) disposed opposite and in alinement with the contacts (43), (42) and (56). Contact (60) is connected with conductor (57) by conductor (61); contact (59) with conductor (53) by conductor ((62) and contact (58) with conductor (44) by conductor (63).

WVith the contacts connected in this manner it is evident when switch blades (42),

Directioa finders.

In order to select the disturbances to be locatedand also to determine the position of reversing switch S, two direction finders, in the nature of hydrophones D 4 and D are submerged off shore well in advance of the detector stations D D and D The positions of the hydrophones with respect to those of the detector stations are such that the disturbance from any splash in the nor-' mal field of fire must contact with either direction finders D or D at least a half a sec end before it encounters detector stations D D or D,. s

The direction finders are connected binauricularly to enable the operator, not only to' hear the disturbance and decidewhether or not it should be located, but also to determine which of the detector stations'D or D the pressure pulse or wave-will strike first, (whether it will strike. detector station D 0r.D so that the switch S may be thrown to the proper position. Each direc tion finding station controls a microphone circuit including ground connection (645), fixed and movable contacts (65) and (66) of the hydrophone direction finder, conductor (67), battery (68), conductor (69), micophone (70) and ground connection Operation and conclusion.

Let it be assl gimed that a proje'ctile enters the Water at a oint, which the listening operator determines to'be to the right of detector station D through the instrumentality of the binauricularly connected stations the diaphragm of detector station D relay R is energized, armature switch Y brought into engagement with contact (28) and circuit 1 closed., Completing this circuit energizes electro-magnet (15"), pulls down the arm- (13) of the recording appa- V ratus and sets the disc (12) in rotation by frictional contact with the drum is rotating at a uniform twentycm. per second. tinues to'rotate until the pressure pulse or wave reaches detector station D whereupon R is energized, armature switch (23) and contact (22) disengaged and the circuit '1 disrupted. Opening circuit 1 deenergizes electro-magnet (15) and permits spring (15) of arm (13) to restore the discv (12) to its original braking position with respect to brake shoe (7), to immediately terminate its rotary movement; Simultaneous with disruption of circuit 1 the armature switch (23) having been placed in engagement with contact (36,), completes circuit 2 energizes electro-magnet (16), pulls down arm (13) of the recording. mechanism and sets the disc (12) in rotation by frictional contact with the rotating drum (8).

The disc (12') continues to rotate until the pressure pulse or wave impinges the diaphragm of detector station D and when this occurs relay is energized, armature switch (34)removed from contact (33) and the circuit (2,) disrupted thereby deenergizing electro-magnet (16) and permitting restoration of disc (12), to braking position with respect to brake-shoe. (7). v

From the preceding it is manifest, since discs (12) and (12) are calibrated togive time readings, the rotation of the discs through a predetermined angle,

(8) which passage of the wave from one station to the other will afi'ord a correct reading of the dif ference in time of arrival of the pressure pulse at the respective stations. Ihe time peripheral speed of The disc (12) con- 7 upon impingement maining station.

during the intervals being obtained, the results are plotted on the board with the proper scales.

In the meantime the operator has opened reversing switch S, released the locking devices in connection with relays R R and R and reset the discs (12) and (12), making the proper zero corrections for the next shot as soon as these are known.

In the present embodiment two discs and (12) are employed, it is to be understood however, one will suflice though the use of two is preferable, as a check on the first reading is thus made possible.

In conclusion it will be seen this invention provides a simple, efficient and accurate recording apparatus which will automatically function to provide the difference in time of arrival of a pressure pulse or wave attwo or more-detector stations and will eliminate the possibility of error and loss of time involved in the devices hereinbefore employed for this purpose.

Although in the foregoing certain elements have been described as best adapted to perform the functions allotted to them, nevertheless it is to be understood that various minor changes may be resortedto within the scope of the appended claims Without departing from or sacrificing any of the principles of this invention.

Having described my invention what I claim as new and wish to secure by Letters Patent is:

1. system of the character specified comprising a pair of detector stations located at spaced and known points, a drum rotating at a constant speed, a movable indicating member located adjacent to and adapted to engage the drum and operable thereby a glven distance in a predetermined time interval, impulse responsive means controlled by the detector stations and including means for moving said indicating member, electrical connections between said detector stations and said impulse responsive means, said connections including means to energize said impulse means when one of said stations is impinged by a pressure pulse or wave and to deenergize said impulse device of the wave with the re- 2. A system of the character specified comprising a pair of detector stations in the nature of compressional wave electroresponsive devices, located at spaced and known points, a drum, means to rotate said drum at a uniform rate of speed, a recording dial located adjacent to and adapted to engage the drum, an electro-magnetic member controlling the action of said dial, electrical connections for said member, said connections including means controlled by one of said stations to energize said member and effect engagement between the dial and the drum whereby to rotate said drum when one of the stations is impinged by a compressional wave and additional means to de-- energize said member and stop the drum when the remaining station is impinged.

3. A system of the character, specified comprising a pair of detector stations in the nature of compressional wave electroresponsive devices, said devices being located at spaced and known points, a drum, means to rotate said drum at a uniform rate of speed, a recording dial located adjacent to and adapted to engage said drum, said dial being provided with time readings predicated stantly moving on its angle of rotation, electro-ma netic means for connecting said dial to an disconnecting it from said nections for said means, said connections including means controlled by said stations for energizing said electro-magnetic means when one of said stations is impinged by a compressional wave and additional means efiectin deenergization of said electromagnetlcmeans upon impingement of the wave with the remaining station, and a switch mechanism cooperating with said stations to vary theorder of their response.

4. A system of the character specified comprising a pair of detector stations in the nature of compressional wave electroresponsive devices, said devices being lo-' cated at spaced and known points, a consurface actuated at a uniformrate of speed, a recording dial situated adjacent to and adapted to engage said surface, said dial being rovided with time readings predicated on its angle of rotation,

e'lectro-magneticmeans for connecting said.

dial to and disconnecting it from said constantly moving surface electrical connections for said means, said connections including means controlled by said stations for energizing said electro-magnetic means when one of said stations is impinged by a compressional wave and additional means efecting deenergization of said electro-mag netic means upon impingement of-the wave with the remaining statlon.

5. A system of the character specified comprising a pair nature of compressional wave electro-responsive devices, said devices being located at spaced and known points a constantly moving surface actuated at a uniform rate of speed, a recording dial situated adjacent to and adapted to engage said surface, said dial bemg provided with time readings preddrum, electrical con-,

of detector stations in the icated on its angle of rotation, electro-magnetic means for'connecting said dial to and connections r said means, said connections including means controlled by said stations for energizing said electro-magnetic means when one of the said stations is impinged by .a compressional wave and additional means effecting deenergization of said electro-magnetic means upon impingement of the wave with the remaining station, and a switch mechanism cooperating with said stations to vary the order of their response.

6. A. system of the character specified comprising a pair of detector stations in the nature of compressional wave electro-responsive devices, said devices being located at spaced and known points, a timing device including a member moving at a uniform rate of speed, an indicator adapted to' give readings in time units directly, electro-magcomprising a pair of detector stations in the nature of compressional wave electro-responsive devices, said devices being located at spaced and known points, a timing device. including a member moving at a uniform rate of speed, an indicator adapted to give readings in time units directly, electromagnetic means for connecting said indicator to and disconnecting it from said moving member, electrical connections between said compressional wave-responsive devices and said electro-magnetic means, said connections includin means for energizin said electro-magnetic means when one 0% said stations is impinged by a compressional wave and additional means efl'ectmg deenergization of said electro-mag'netic means upon impingement of the wave at the remaining station and a switch mechanism cooperating with saidstations to vary the order of their response. 7 I

EDWARD B; STEPHENSON. 

